Automatic pressure relief device for calenders and the like



Aug. 27, 1957 G. H. SCHIFFER 2,803,896

AUTOMATIC PRESSURE RELIEF DEVICE FOR CALENDERS AND THE LIKE Filed March 22. 1956 2 Shee ts-Sheet 1 JIHJIIIIIIIII I I II 1 I 4r///////// ci l' g ll 5 1 E H] I l i I i I! g m" INVENTOP AUTOMATIC PRESSURE RELIEF DEVICE FOR CALENDERS'AND THE LIKE Filed March 22. 1956 27, 1957 G. H. SCHIFFER 2 2 Sheets-Sheet 2 'MQQA 22/0 I) a 0/.-

KUTOMATIC PRESSURE RELIEF DEVICE FOR GALENDERS AND THE LIKE tlGiinther Heinzi Schilfer Krefeld, Germany, assignor to I lohqnKleinewefers Siihne, Krefeld, Germany 7 The present invention relates-to an automatic pressure reliefdvice for calendars J and thelike.

"It 'is known to sew together piece gOdst0 an endless piece -of cloth forallowing a continuous operation of ealendersand"thelike. In order to prevent damage to the elastic calender-roll when a transverse" seam passes 'sithrough the calender rolls, the operator has'to pay very closeattention to 'the passing m'aterial'in order to re- -leasefthe pressure on" the respective calender roll or rolls -'shortly'-prior to the seam passing through the calender rolls. Inasmuch i as this requires the continuous attention 0f the operator, While the safety factor is nevertheless ra-ther low, it 'has' been suggested-to scan the seam: by means ofa mechtinicahelectrical or tloptical-electrical "*feeleror'. by means of compressed air'operated feelers and to use the impulses conveyedby'such'feeler to: initiate a rnechanism for r relieving the pressure onthe respective calender-rolhonrolls. However, suchreelers have proved insufiicient inasmuch ;asthey also respond 7 to vi'bra-tions of the machine and furthermore .to knots or--spot-like "dirt accumulations "so that the'prtessure is relieved at the improper time with 'the'resultf that faulty spots -i-n the goods willbe unavoidable.

It is,ther efore,- anobject of-the present 'invention to providean-automatic ,pressure relieving device for. calenders and the like which will overcomethe above-mentioned drawback.

-It' is anotherobject "of this invention to provide an automatic pressure relief device "for calenders' and the "like whichwill; properly relieve the pressure on the calender roll-orrollswvhen atransverse seam is about to pass between the calender'rolls While it will not .react to machineivibrations and knots or spot-like dirt accumulations.

E These and other objects and advantages of the inven- -tionwill appear more clearly from "the following specification I in connectionwith the accompanying drawings, inwhich:

uFigallwrepresents adiagrammatictop View of a'le'ngth rofycloth 'containing a transverse seam, said 'view also showing scanning-feelers arranged in conformity with the invention" for -scanning the seam.

Fig. 2t is a sidewiew of the arrangement shownin Fig! 3 represents a mechanical-electrical scanninglever.

. Fig.1 4tillustrates an electronic control circuit foruse tin connection with :the t arrangement of Fig. 1.

General arrangement According to the present invention two feelers are arranged in ,spaced relationship from each other and 'from the nip of the calender rolls for feeling or scanning a transverse seamin apiece .of cloth passing betweenthe feelers and one ofthe calender rolls. The said two feelers are-offset with regard to each other in a direction transverse ,to the direction of movement of the cloth toward the nip of the tcalender rolls. "When a transverse seam in the clothiisflfeltby the feelers, an impulse-is ."c'onveyed bysaidfeelers to an-electric circuit, which, howr ever, responds only whenthe impulses of both feelers at the scanning points have beeninitiated at a time in- "tervalwhich corresponds to the speedof movement of 511said cloth over a distance corresponding to the distance betweenthe scanning points. Therefor'e,all impulses which have not been produced within the said time interval will remain without any effect, thereby, preventing. arfaulty relief of the pressure upon the respective calen- 'der roll or rolls. The timelinterval for causing the 'electric circuit to respond, i. e., to act upon the means 'reliev- 'ing the pressure on the respective calender roll or rolls is adjustable in conformity with the required traveling jspeed of the respective, piece of cloth. -Inasmuch as the distance from the scanning point to the nip between the ."calender rolls is fixed, it will beaappreciated" that also the'time interval for switching on and on the pressure 'r'eliefme'chanism following the scanning impulses will be dependent onthespeed of rotation of the rolls, and also this timeinterval is variable in conformity with the desired conditions.

:lStrucrural arrangement Referring now to the drawings 'in'detaiL the', piece of cloth 1"is' assumed to'move in'the direction of the arrow -A towardandthrough the'calender rollsiz and3. The

' roll ZrepreSentsQan elastic r'oll,'while the roll 3is a steel r511. -At' apoint where the' goods 'are'supported, for instance) by'the"feeding roll, or,'in conformity with Figs. -1 and'2,=by theela'sticroll 2,"twofe eclers 5 and 6 are 'arranged in spaced 'relationship" to e'ach' "other "and 'js'paced from the nip between the-rolls 2 and 3. As will be'cl'early "-evidenflfrorn'Fig. 1,'thefeelers'5'and"6 are "offset with "regard to each-other in'la directi'on transversetothe directionof movement of '.the"cloth" 1. This means'that one-feeler; namely feelersistahead of the "other "feeler, namely feelertS when'lookinginnhe direction fot "the arrow in'Fig. 1, while saidfeelers are not in alignment with each dtherwhenloo'king in'thedirec'tion of movement of sa'idjpiece of cloth. Bothifee'lers willi'thus successively respond when a seam 4"pa"sses between said feelers and the roll- 2. *Whenthese feelers respond, they closea'co'ntact which conveys an electric current impulseto an' electric circuit. These impulses are evaluated automatically in' this circuit and, providedthe timeinterv'al 'between-the=impulses"caused 'by the 'fe ei'ers s and "6i-corresporrds-to the adjusted-value of 'traveling'speed of the cloth from one scanningpoint to another scaniringpoint, the-said electric circuit will actuate a relay w whichin its "turn brings about arelief of the pressure norrnally urging the' roll Zagainst the'roll 3.

The travelingspeedof the"cloth-isadjusted on the 'con trol? device'7by meansof a pointer 7asweeping overa isrlial flb. Furthermore, the control device-is so designed tthattt-he pressure relie'f ofthe respective calender roll'or 'rolls iseffecteddn the proper movement; i. e., sh'ortlybeafore :the seam passes through the'r'olls while the pres- =sure relief device"-is" -rnade'ineffectiveshortly after the "searmhas'passed between ther'dlls. The'control'of the time interval ibe'tweenfthe impulses caused by tl16 4ZWO feeIersS and 6vcan be effected in .di ifer'e'nt nlanner, for instance {by means of aedelayed' action relay or by a step by astep-switch mechanism working. in! a purely r m'e'ehanical manner. At-higherrtraveling .speedspffthe goods, however, =the time 1 interval between .the twofiimpulses is so short that arrangements: of-ithe above 'rnentioned type "working by-rneans of a delayed =action rielay Ion :by a" purely mechanical step by step switch will not any longer work satisfactorily. .Therefore, in further 'devel'opmenttof. ithe invention, :there :is qiprovided an :iele'ctronicc control circuit vaccordingwto 1 which the wharging and dischangingitime of a condenser by -mea-ns1of athree thyratronsifis used-fon ex- I 3 amining the respective time interval. With such an arrangement, two thyratrons may be employed for contact scanning, whereas by means of the third thyratron, the duration of the pressure relief of the respective, calender roll or rolls up to the time the same has fully 'passed through the rollscan be adjusted.

The control operation in the control device 7 will then be as follows: When the first feeler 5 closes its contact 5, the negative grid voltage of the first thyratron 20 is cancelled, and the thyratron 20 fires. As a result thereof, it charges a condenser 23 which in turn causes the operating voltage of the tube 20 to drop below the firing voltage so that the tube dies again. The complete charging of the condenser 23 is secured even when the duration of a contact amounts only to three thousandths of a second. The condenser 23 now discharges itself through a variable resistance 7 which conveys the working potential of the second thyratron 21 to the feeler 6 with the contact 6'. The adjustable resistance 7 thus determines the effective time interval, i. e., the speed of movement or" the cloth at which the pressure relief device will be effective. When the potential still corresponds to a charge which is in conformity with the adjusted discharge time or is greater than the latter, also the second thyratron 21 can fire when the feeler 6 closes its contact. By closing its contact 8", the relay 8 in the anode circuit initiates the pressure relief of the respective calender roll or rolls, while closing of contact 8" of relay 8 initiates the operation of the third thyratron 22. Movement of switch 8 into the position shown in Fig. 4 brings about the discharge of the condenser 24 through a variable resistor. The third thyratron 22 makes the device7 ineffective and stops the same. The time of readiness of the device 7 begins anew with the last closure of the first contact of the feeler 5.

Closure of the contact 8' actuates an electromagnet 9 the armature 39 of which displaces the piston 38 of a hydraulic control valve toward the left whereby the pressure conduit 40 of the hydraulic cylinder of the calender is connected to the discharge conduit 42. As a result 1.

thereof, the pressure fluid is discharged from the hydraulic cylinder 41 so that the lower roller 2 of the calender moves downwardly and the distance between the rollers 2 and 3 is increased. The pressure fluid is delivered by a hydraulic pump 31 and passes through conduits 32 and 36 to the hydraulic control valve. A pressure fluid storage container 35 connected to the conduit 32 will always assure that when pressure is required in the hydraulic cylinder 41, pressure will immediately be avail able so that the supply of pressure to the hydraulic cylinder will be effected instantly.

Fig. 3 illustrates a mechanical-electrical feeler which consists of a two arm lever 10 having one end thereof provided with a roll 10a, while the other end of the lever 10 rests against a guiding bolt 11. The lever 10 is fastened by a fish-plate 12 to a support 13, while the pressure exerted upon the roll 10a may be varied by means of a spring 15. An adjustable screw 14 acts upon and may vary the thrust of the spring 15 to thereby vary the pressure exerted upon the roll 10a. The adjustment of the spring 15 is important in order to avoid a fluttering of the lever in conformity with the conditions of the working process. The establishment of a contact is effected by means of a finally adjustable contact 17 and 5 (6'), the contact 17 being connected to the fishplate 12 by means of an insulating member 16. The fine adjustment of the contact fork can be effected in such a manner that, for instance, the feelers will not respond when butt joint seams are encountered but will safely respond when the seam interconnects overlapping portions of the cloth.

It is, of course, understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings, but also comprises any modifications within the scopeof the appended claims.

What I claim is:

1. In an automatic pressure relief device for use in connection with calender rolls arranged to pass textile material therebetween, which material has a seam transverse to the direction of movement of said textile material toward and between said calender rolls, the combination of: a first feeler having first contact means associated therewith and being arranged ahead of the nip of said rolls when looking in the direction of movement of said textile material, said first feeler comprising a first member for contact with said textile material, said first member being operable by a transverse seam in the material passing therebelow to close said contact means; a second feeler having second contact means associated th rewith and being arranged ahead of said first feeler when looking in the direction of movement of said textile material, said second feeler comprising a second memher for contact with said textile material, said second member being operable by a transverse seam in said textile material to close said second contact means; said feelers being offset with regard to each other in a direction transverse to the direction of movement of said textile material, pressure exerting means associated with at least one of said calender rolls for continuously urging said rolls relative toward each other; and means operatively connected with said members and arranged to make said pressure exerting means temporarily ineffective in response to said members being sequentially operated within a time interval corresponding to the time of travel of said material over a distance equaling the projection of the straight line distance between said members upon the longitudinal axis of the textile material passed between said calender rolls.

2. An arrangement according to claim 1, in which said members are provided with roller means for contact with said textile material.

3. In an automatic pressure relief device for use in connection with calender rolls arranged to pass textile material therebetween, which material has a seam transverse to the direction of movement of said textile material toward and between said calender rolls, the combination of: a first feeler arranged ahead of the nip of said rollers when looking in the direction of movement of said textile material, a second feeler arranged ahead of said first feeler when looking in the direction of movement of said textile material and offset with regard to said first feeler in a direction transverse to the direction of movement of said textile material, each of said feelers comprising a stationary contact member and a movable contact member and also comprising a lever carrying said movable contact member and having an element for contact with said textile material, adjustable spring means continuously urging said contact members away from each other; pressure exerting means associated with at least one of said calender rolls for continuously urging said calender rolls relative toward each other; and means operatively connected to said contact members and arranged to make said pressure exerting means temporarily ineffective in response to the two contact members of each feeler sequentially contacting each other within a time interval corresponding to the time of travel of said material over a distance equaling the projection of the straight line distance between said two feelers upon the longitudinal axis of the textile material passed between said calender rolls.

4. In an automatic pressure relief device for use in connection with calender rolls arranged to pass textile material therebetween, which material has a seam trans verse to the direction of movement of said textile material toward and between said calender rolls, the combination of: a first feeler having first contact means associated therewith and being arranged ahead of the nip of said rolls when looking inthe direction of movement of said textile material, said first feeler compris ing a first member for contact'with said textile material,

said first member being operable by a transverse scam in the material passing therebelow to close said contact means; a second feeler having second contact means associated therewith and being arranged ahead of said first feeler when looking in the direction of movement of said textile material, said second feeler comprising a second member for contact with said textile material, said "second member being operable by a transverse seam in said textile material to close said second contact means; said feelers being oflset with regard to each other in a direction transverse to the direction of movement of said textile material, electronic circuit means including electronic control means, each of said contact means respectively associated with said first and second feeler being arranged to be closed in response to the actuation of the respective feeler by a transverse seam in the textile material passing therebelow, and an electronic control circuit including electronic tubes and a condenser, said electronic control circuit having a first branch arranged to be closed in response to the closure of said first circuit means to thereby charge a condenser through one of said electronic tubes, said electronic circuit means also including a second branch circuit arranged to fire another one of said electronic tubes in response to the contact means of said second feeler closing at a certain time following the closure time of said first contact means, pressure exerting means associated with at least one of said calender rolls for continuously urging'said rolls relative toward each other; and means arranged to make said pressure exerting means temporarily ineffective in response to the firing of said second electronic tube at a certain time following the firing of said first electronic tube and corresponding to the time required for the travel of said seam from said first feeler to said second feeler.

5. An arrangement according to claim 4 which in cludes a third branch circuit with an additional electronic tube adapted to be fired simultaneously with said second electronic tube for making said means ineffective which temporarily makes said pressure exerting means ineffective to thereby restore the conditions prior to said feelers being actuated by said transverse seam.

References Cited in the file of this patent UNITED STATES PATENTS 

